The examples used in the description refer to a missile as an example of an advanced weapon. This is not meant to limit the description to a missile and the techniques described are applicable to any advanced weapon that can be programmed or configured in any way as will be obvious to the skilled reader.
It is common to have two or more separate operational modes incorporated in a weapon. The main mode being the mode where the weapon is to be used as it is intended, i.e. in an operational mode as a weapon. It is common to have a second non-operative mode, i.e. a maintenance mode, allowing critical maintenance operations like testing of major functionality, simulating arming of the weapon, or writing/deleting software/firmware in persistent memory in the weapon. An advanced weapon like a cruise missile can have separate SW running in the two different modes.
There are many ways to communicate with a missile when it is in a non-operative mode. The most common being some electrical communication protocol like Ethernet over either a separate connector (non-umbilical), or using one or more of the electrical pins adapted to this in an umbilical connector, or simply using MIL-STD-1553 standard protocol that is defined in the standard MIL-STD-1760 defining a standardized electrical interface between a military aircraft and its stores, e.g. a missile. MIL-STD-1760 defines the electrical characteristics of the signals at the interface, as well as the connector and pin assignments of all the signals used in the interface.
In US2015082975 it is described how operations, which are not possible only using MIL-STD-1760, can be implemented using an interface bridge as an additional HW between the aircraft and the weapon. In this solution both typical maintenance operations and typical operative operations that do not conform to the MIL-STD-1760-standard can be performed. In the present invention, the non-conformal operations are limited to maintenance mode for avoiding the use of additional HW on a carrier aircraft.
The transition from operational mode to a non-operational mode is critical. It is important that this transition is made in the safest and most reliable way possible for minimizing the risk of unintentionally entering a non-operational mode.
Mode changing functionality in missiles can be implemented in several ways. Elements that can be used are for instance: authorization of a user (for instance according to the MIL-STD-1553 protocol), strict procedures prior to sending critical software (SW) commands, “Remove before flight” hardware (HW), e.g. HW switches closed by removing a splint, that inhibit the before mentioned transition of operation mode. A combination of two or more of these is also feasible.
It is common to use some sort of physical inhibit function in combination with a SW command. Using a HW element has the advantage of being easier to observe and is less prone to bugs as is the case for a SW solution. In other words, a HW solution does not need the extensive testing that a SW solution would need when it comes to proving reliability.
The disadvantage of HW, like for instance a physical switch, is that it in some way needs to be accessible from the outside of the weapon. This poses potential problems and maintenance issues.
An umbilical connector used for communicating with a missile is defined in the military standard MIL-STD-1760. All pins in this connector are occupied by some function. To be allowed to use a store on an aircraft, the store must strictly adhere to said standard. A store is a device intended for internal or external carriage and which is mounted on aircraft suspension and release equipment.
A missile is military equipment with a set security classification. The set classification can in some cases be different from the classification of the equipment it is connected to. If the equipment in question has a lower classification than the equipment it is connected to it is important to ensure that no classified information from equipment with higher classification is passed to equipment with a lower classification in a permanent way.
The present invention provides a secure way of assuring that no classified information can pass from equipment with a high classification, like an aircraft, to equipment with a lower classification, like a missile, while conforming to MIL-STD-1760 using an existing umbilical connecting said missile to said aircraft.